Modern plasmapheresis techniques for collecting blood plasma from a donor permit a donor to give two units of blood (aout 600 ml. each) at one time, but after the withdrawal of one unit of blood, the red cells must be returned to the donor before the second unit is withdrawn. In early blood collection equipment, it was necessary to disconnect a first blood container from a blood flow tube after the return of the red blood cells so that the second blood container could subsequently be connected to the blood flow tube to return the red cells obtained from the second unit of blood.
To rectify this situation, a blood administration method and system was designed wherein the containers for the first and second batches of red blood cells were connected to a different inlet for the same blood flow tube. This administration set and the blood collection assembly employed therewith is illustrated by U.S. Pat. No. 3,459,182 to Henry Naftulin. The blood administration system shown in the Naftulin patent obviates the necessity to disconnect a first blood container from a blood flow tube before red cells are returned to the donor from a second blood container, and thus provides a sterile and more effective administration set. However, the blood collection system disclosed by the Naftulin patent is typical of presently known blood collection systems currently employed for the withdrawal of whole blood from a donor. In such systems, two flexible collection bags, each containing about 50 or 60 ml. of sodium citrate solution are each connected by tubing to a separate Y connector. One of these Y connectors communicates through a tube with a needle for drawing blood from the donor, while the second Y connector is joined both to the first Y connector and also to an administration set for saline solution and the red blood cells.
To use such prior blood collection sets, the phlebotomy or venipuncture needle is placed in the vein of a donor after first clamping off the connecting tube between one blood bag and the associated Y connector with a hemostat. Additional clamps or hemostats are also placed on the connection between the blood administration set and the Y connector joined therewith. Control of the blood collection process is accomplished by manually moving the hemostats to selectively clamp off other tubes in the collection set at desired times. This process is not only time consuming, but is subject to error if a hemostat is not secured to properly shut off a tube.
Even more important is the necessity to properly position the hemostat between a blood collection bag which is not in use and the venipuncture needle. It is a natural practice to place the hemostat at some position along the tube between the blood collection bag and the associated Y connector, for this placement is relatively easy to accomplish in a short time. However, if the hemostat is not actually placed on the Y connector to close off one branch thereof to an unused blood collection bag, blood can collect in the dead space between the Y connector and the hemostat. This static blood is likely to clot during portions of the procedure when there is little or no flow through the adjacent branches of the Y connector. Then, when the hemostat is released, the clot will prevent flow in the newly opened branch to the blood bag or, in the alternative, may break loose to clog the venipuncture needle. The same problem results when valving means are provided at the inlet to the blood collection bag.
The blood collection bags or containers employed with a blood collection set are normally disposed after use, and such containers, as disclosed by the aforemention Naftulin patent, often constitute a bag of thin, flexible material having an inlet tube sealed thereto for blood and two additional access ports. These access ports are usually identical and consist of a short tube having a pierceable diaphragm at the inner end thereof; sterility being maintained by capping the outer end with a frangible cap as illustrated in U.S. Pat. No. 3,509,879 to L. N. Bathish et al. The diaphragm must be pierced and entered by a needle or spike in order to add or remove any solution or fluid content from the container. Flexible containers of this type are well known to the prior art as illustrated by U.S. Pat. Nos. 2,894,510 and 2,950,716 to D. Bellamy, Jr., as well as a second U.S. Pat. No. 3,782,382 to Henry Naftulin et al.
The structure of prior art blood collection bags or containers results in some inherent problems when the bags must be handled in the manner required by conventional plasmapheresis techniques. For example, the bags are extremely flexible, and when filled with fluid are difficult to handle and hold. The short access ports projecting from the body of the bag are formed of flexible tubing and are difficult to grasp. These ports are even more difficult to use for purposes of stabilizing the bag while a needle is inserted through the pierceable diaphragm closing a port. Often, the bag shifts during this piercing operation and the needle or spike penetrates the sidewalls of the bag or the access port tube. This causes the contents of the bag to leak and sometimes results in injury to the fingers or hand of the operator. Also, an operator attempting to rapidly manipulate two blood collection bags and properly pierce and connect four separate access ports is very likely to pierce the wrong port and accomplish an erroneous connection. Once this is done, the sterility of the fluid in an associated collection container can be destroyed.
It is a primary object of the present invention to provide a novel and improved plasmapheresis assembly which requires no pierceable needle connections to accomplish the addition or removal of fluids from portions of the system.
Another object of the present invention is to provide a novel and improved plasmapheresis assembly which incorporates unique container access connectors and mating conduit connectors to insure that proper connections are made to accomplish a plasmapheresis operation.
A further object of the present invention is to provide a novel and improved plasmapheresis assembly employing externally operated Y valve units to positively close the branch conduits of the assembly and preclude the formation of dead spaces where blood clots may form.
Another object of the present invention is to provide a novel and improved plasmapheresis assembly which includes flexible fluid collection bags having rigid access port structures which may be positively gripped to facilitate rapid manipulation of the bag.
A still further object of the present invention is to provide a novel and improved plasmapheresis assembly constructed of simple, inexpensive parts which may be rapidly and safely assembled and employed to efficiently accomplish plasmapheresis.